Female electrical terminals provided by blanking and bending sheet metal and comprising two pairs of mutually opposite leaf spring laminas, a first pair of shorter laminas and a second pair of longer laminas, are currently known and widespread.
Such leaf spring laminas have mutually opposite protrusions which are intended for contact with an interposed blade-like male terminal and are provided on the shorter laminas and on the longer laminas so as to be offset, so as to allow soft insertion of the blade-like male terminal.
The expression “soft insertion” means that the relative force to be imparted between the female terminal and the male terminal to insert the male terminal between the leaf spring laminas of the female terminal is lower than the force that would have to be applied if the laminas had the protrusions at the same height; the offset of the protrusions on the laminas causes the two pairs of laminas to be divaricated at different times, first the pair of long laminas and then the pair of short laminas.
Further, the offset contact points produced by the different length of the two pairs of laminas ensure optimum contact between the female terminal and the blade-like male terminal, even though the female terminal is not perfectly axially aligned with the hole of the male terminal.
Known terminals have the drawback that they are easily disengageable from the male terminal, and said disengagement can be determined for example by the vibrations to which the powered device is subjected, be it an electric motor, a transformer, or any other similar device; mutual disengagement of the female terminal and of the male terminal causes the interruption of the electrical connection, leading to complete or partial failure to operate of the object on which said terminals are fitted.